The present invention relates to a large screen projector, and more particularly to a multi-screen projector having a plurality of unit module projectors stacked one upon another.
A large screen projector of this type is known as disclosed, e.g., in the specification of U.S. Pat. No. 4,536,056 filed on Oct. 7, 1983, assigned to Hitachi, Ltd., and entitled as "Background Projector Apparatus". According to the teachings of this art, a background projector apparatus can be readily manufactured which has a screen size smaller than or equal to about 100 inches. However, a background projector apparatus having a larger screen greater than or equal to about 150 inches requires a considerably large size Fresnel lens so that such a large screen background projector apparatus is very difficult to be manufactured.
There is also known a configuration scheme wherein a plurality of small unit module projectors each having a screen size of about 40 inches are juxtaposed side by side and one upon another to form a single large size screen. With this module type configuration, however, a light applied to each unit module screen of the projectors juxtaposed in the vertical direction is emitted therefrom within the range of plus/minus 6 degrees in the vertical direction relative to the normal direction of the screen. Therefore, an image as viewed from audiences outside the directivity becomes dark. This problem can be solved by making the vertical directivity of each screen of a unit module projector as wide as about plus/minus 30 degrees. This solution however gives rise to another problem that the overall screen becomes dark.